1. Field of the Invention
This invention relates generally to a video cassette auto-changer, that is, an apparatus for selectively supplying, to a plurality of reproducing and/or recording devices or VTRs, video tape cassettes stored in a large number of respective cassette storage bins.
2. Description of the Prior Art
A video cassette auto-changer has been provided, for example, for use by broadcasting stations, so that a large number of video tape cassettes can be automatically selectively loaded in sequence into a plurality of video tape recorders so as to permit continuous video reproducing and/or recording for an extended time. In a known video cassette auto-changer, a large number of cassette storage bins are arrayed vertically and horizontally in an arrangement of stacks thereof, with a plurality of VTRs disposed at one end of the stack arrangement, and with a cassette transporting device being provided for selectively transporting cassettes between the storage bins and the VTRs. Having in mind the relatively large dimensions of the stack arrangement in orthogonally related directions, for example, in vertical and horizontal directions, the cassette transporting device may comprise a carriage adapted to receive a cassette from, and to discharge a cassette into a selected one of the storage bins VTRs with which the carriage is registered, a movable guide rail extending in one of the orthogonally related directions, for example, vertically, and having a length at least as large as the height of the stack arrangement with the carriage being mounted for vertical movements along the movable guide rail, and fixed guide rails extending in the other orthogonally related direction, that is, horizontally at the top and bottom of the stack arrangement along the length of the latter, with sliders being movable along the fixed guide rails and attached to the ends of the movable guide rail. By effecting movements of the sliders along the fixed guide rails and of the carriage along the movable guide rail, the carriage can be brought into selective registry with the various cassette storage bins and VTRs. However, by reason of the relatively large space occupied by the stack arrangement, it is at least difficult and costly, and in some instances even impossible, to achieve precise parallel alignment of the upper and lower fixed guide rails with the result that the sliders, when rigidly connected to the ends of the movable guide rail for movably mounting the latter on the fixed guide rails, may jam relative to the latter.
Further, in the above-described video cassette auto-changer according to the prior art, it is necessary to transmit electrical control signals or the like over large distances, for example, to the carriage as the latter is moved over relatively large vertical and horizontal distances for selectively registering with any one of the large number of cassette storage bins or the plurality of VTRs. For this purpose, it has been proposed to employ an elastically coiled electrical cord for transmitting the electrical control or driving signals to the movable carriage or the like, with the intention that the elastically coiled cord will be automatically extended and contracted in accordance with movements of the carriage away from and toward, respectively, a fixed terminus or receptacle from with the coiled cord extends. Alternatively, it has been proposed to use a flat, flexibly resilient cable as the electrical connecting member and to increase the inherent resiliency of the flat cable by mounting a leaf spring therealong as a guide member to prevent entangling of the cable in adjacent structures during movements of the carriage. As still another possible arrangement of the electrical connecting member, it has been proposed to employ therefor a cable inserted, for at least part of its length, in a resiliently flexible tube which tends to keep the cable straight, but which can be resiliently bent up to approximately a 180.degree. turn for accommodating movements of the carriage. However, the foregoing schemes for controlling and preventing snagging of the electrical connecting member are all burdened with respective disadvantages. When an elastically coiled electric cord is used, the maximum length of the extended cord is about three times its minimum or contracted length. Thus, the elastically coiled cord, even when fully contracted, takes up more space than is desired. Similarly, when a flat, flexibly resilient cable is employed either alone or with a leaf spring or the like mounted along the cable to increase its resiliency, or when the cable is inserted in a resilient tube, undesirably large spaces are required for such arrangements particularly when large movements of the carriage are to be effected and sharp bends in the cable are to be avoided.